The accumulation of electric charge on a surface is called static electricity, and a lightning conductor is made of copper, so this Grade 8 sheet opens with charge buildup and its protection. An earthquake, a seismograph and the crust follow in the answers.
Key Takeaways
Charge accumulating on a surface is static electricity (Q1).
A lightning conductor is made of copper (Q2).
Q3 records an earthquake among the answers.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.The accumulation of electric charge on the surface of an object is called:
(a) Static electricity(b) Current electricity(c) Magnetism(d) Induction
2.A lightning conductor is made of:
(a) Copper(b) Rubber(c) Wood(d) Glass
3.The sudden shaking of the surface of the Earth is called:
(a) Earthquake(b) Cyclone(c) Tsunami(d) Landslide
4.The instrument used to detect and record earthquakes is called a:
6.The point on the surface of the Earth directly above the origin of an earthquake is called the:
(a) Epicentre(b) Focus(c) Fault line(d) Seismic zone
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.What is static electricity? How is it produced?
8.What is an electroscope? What is it used for?
9.Why is it unsafe to take shelter under a tall tree during lightning?
10.What is an earthquake? What causes earthquakes?
11.Name the three layers of the Earth.
12.What is the Richter scale? What does it measure?
13.How does a lightning conductor protect a tall building?
14.Write any two precautions to be taken during an earthquake.
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A lightning flash is seen and its thunder is heard 6 seconds later. If the speed of sound is 340 m/s, find the distance of the lightning from the observer.
16.The epicentre of an earthquake is 150 km from a seismograph station. If the seismic waves travel at 5 km/s, how long will they take to reach the station?
17.An earthquake generates P-waves that travel at 8 km/s. If the epicentre is 400 km away, calculate the time taken for the waves to arrive at the station.
18.The distance between a cloud and the ground is 3 km. The thunder is heard 8.8 seconds after the lightning flash. Find the speed of sound from this observation.
19.Two seismograph stations are at distances of 200 km and 350 km from the epicentre of an earthquake. If the waves travel at 7 km/s, find the difference in their arrival times.
20.The light from a lightning flash 3 km away reaches an observer almost instantly. If light travels at 3 × 10⁸ m/s, calculate the time taken by the light to reach the observer.
Answer Key
1. a) Static electricity
2. a) Copper
3. a) Earthquake
4. a) Seismograph
5. a) Crust
6. a) Epicentre
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End of Worksheet
People Also Ask
What is the accumulation of charge on a surface called?
Static electricity, option (a) in this worksheet (Q1).
What is a lightning conductor made of?
Copper, option (a) in this worksheet (Q2).
What does a seismograph measure?
Earthquakes — option (a) in this worksheet (Q4).
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